A University of Maryland study warns that relaxing Florida’s school-entry vaccine requirements could lead to a severe measles resurgence, with a vulnerable population and rising cases urging urgent reconsideration.
A proposal to scrap Florida’s school-entry requirement for the measles, mumps and rubella vaccine could open the door to a major measles outbreak in a state already approaching a dangerous threshold, according to a University of Maryland study published in the Proceedings of the National Academy of Sciences. The model, which drew on a 2025 outbreak in Texas and Florida’s vaccination rates, found that measles could become entrenched in the state and, because of frequent travel in and out of Florida, could help drive spread elsewhere in the United States.
The researchers, Alice Oveson and Abba B. Gumel, said Florida’s herd immunity would begin to unravel if MMR coverage fell below roughly 93% to 94%. The state is already below that level, they wrote, with coverage at 91.6% among children and 92.5% among adults. The study also estimated that 7.5% of adults aged 18 and older are either unvaccinated or lack natural immunity, leaving what Oveson described as a large pool of people who remain highly vulnerable to infection.
The warning lands as national and state measles trends remain concerning. The Centers for Disease Control and Prevention says kindergarten MMR coverage has fallen from 95.2% in the 2019-20 school year to 92.4% in the 2025-26 school year, leaving about 280,000 kindergartners at risk. In Florida, WUSF reported in March that the state had recorded 124 measles cases since the start of the year, with vaccination rates still below the 95% level generally needed to block sustained spread.
Oveson said the absence of a large outbreak so far is no guarantee of safety, telling Medscape that part of the reason Florida has avoided a much larger surge may simply be luck. The study concluded that if lawmakers removed the MMR mandate, childhood coverage could sink as low as 82% in a worst-case scenario, or 90% in a more optimistic one. Under the worst-case model, a pronounced outbreak could emerge within three to five years, with peak infection rates reaching 260 to 315 cases per 100,000 children and 135 to 160 per 100,000 adults.
The Florida chapter of the American Academy of Pediatrics has pushed back against any weakening of vaccine rules. Jennifer Takagishi, the group’s president, said more families are refusing or delaying the MMR shot and that some continue to cite the long-discredited claim that vaccines cause autism. She said others are asking for early vaccination because they are worried about outbreaks, although doses given before 12 months do not count towards the standard two-dose series. Takagishi also warned that the issue is likely to return when lawmakers meet again in March 2027, after the state health department backed away from a plan to broaden exemptions for “moral or ethical beliefs” and said it would hold a public meeting on 8 October.
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